This invention is directed generally to locking mechanisms and more particularly to an apparatus which covers the hitch ball receptacle of a trailer coupler thereby denying access to the receptacle and preventing unauthorized movement of the trailer.
Several locking devices have previously been devised which cover the hitch ball receptacle or opening of a conventional ball and socket type trailer coupler to prevent thieves from connecting a tractor vehicle to the trailer and hauling the trailer off. In prior devices the retaining member can be moved into the receptacle only by moving or depressing a part extending to the outside of the device. This part is either the retaining member itself, an extension of the retaining member or an attachment to the retaining member. In these prior devices, the movement of the retaining member into the hitch ball receptacle of the coupler is independent of the operation of the lock. Only after the retaining member is moved into the hitch ball receptacle, is the lock activated to hold the retaining member in place or to block access to a means of releasing the retaining member. In most prior art devices, the lock is a separate padlock which is not permanently affixed to the device. There are no devices known to this inventor in which the act of locking a lock permanently affixed to the device causes the retaining member to move into the hitch ball receptacle.
In Foote, U.S. Pat. No. 3,526,110 a set screw must be adjusted with a separate tool in order to properly operate the locking device. In Longnecker, U.S. Pat. No. 3,780,546 a separate padlock is used to secure the device to the trailer coupler.
In Bulle, U.S. Pat. No. 4,291,557 the retaining member is spring loaded allowing it to automatically retract as the device is slipped over the coupler and then to automatically project into the hitch ball receptacle when the device is in place.
The locking device is removed through a key operated, spring biased cam which retracts the retaining member from the hitch ball receptacle. With the retaining member retracted, the locking device can then be removed from the coupler. However, upon removal of the locking device from the coupler, the retaining member is exposed and is subject to being bent or damaged.